The Exorcist is to exorcisms what The Godfather is to the Mafia: That is, the film is the font of every cliché about its subject and barely rooted in fact. Just as Francis Ford Coppola’s 1972 mobster classic invented many of its gangland rituals out of thin air, William Friedkin’s landmark 1973 horror movie didn’t have much to do with the real-life case it was based on. One could view Friedkin’s new documentary, The Devil and Father Amorth, as an act of atonement, since it involves Friedkin shooting a real-life exorcism in all its mundanity. But more than that, the film feels like a director thinking back on the work that defined his career, for better and worse.

“At the time I made the film The Exorcist, I had never seen an exorcism,” Friedkin intones over footage of Reverend Gabriele Amorth walking down a nondescript corridor. “More than 40 years later, I witnessed the one you are about to see.” The Devil and Father Amorth is a low-budget affair filmed on small, cheap cameras, but it’s nonetheless sporadically arresting, with hints of the gritty verisimilitude that made Friedkin one of the premier directors of the 1970s. As a documentary, it’s frustratingly basic, running only 68 minutes and not doing much to dig into the complex discussions around the Catholic Church’s continued practice of exorcisms. As a work of self-reflection, it’s a little more interesting.

Reverend Amorth, who died in 2016 not long after Friedkin made this movie, was reported to have performed more than 160,000 exorcisms over his career. Near the end of his life, he allowed Friedkin to record him performing one on an Italian woman named Cristina, her ninth exorcism overall. Mixed in with that footage is Friedkin waxing lyrical about the ritual itself and the power of belief. He notes that some 500,000 Italians have undergone exorcisms, and consults with psychiatrists who argue that there is a subconscious, performative act to the ceremony on both sides.

The footage Friedkin captures is undeniably fascinating. This isn’t the dark, chilly, atmospherically lit bedroom of The Exorcist, where Fathers Lankester Merrin (Max von Sydow) and Damien Karras (Jason Miller) confront the demon occupying young Regan MacNeil’s (Linda Blair) body. Cristina is sitting in an office in the daytime, next to Reverend Amorth and surrounded by dozens of family members. The furniture doesn’t shake, and Cristina’s head doesn’t revolve 360 degrees, but as Amorth prays to her in Latin, she does scream at him and thrash in her chair, her voice taking on an unnatural, guttural tone.

Friedkin himself seems convinced—by Cristina’s behavior, by Amorth’s pious conviction—but he does take the footage to disbelieving experts who deconstruct it, noting that Cristina’s own deep belief in the ritual might cause her to enter a sort of trance state. Still, The Devil and Father Amorth has neither the time nor, judging from the production values, the resources to really dig into the details on either side. The documentary’s most revealing scene comes in a conversation with Los Angeles Auxiliary Bishop Robert Barron, who tells Friedkin he himself would be too afraid to perform an exorcism, considering himself not learned and holy enough for the task.

In Barron’s words, demonic possession is delicate theological territory to walk on. But in making The Exorcist and now filming this documentary, Friedkin charged right onto that holy ground, turning it into something thrilling. The footage from The Devil and Father Amorth of Cristina’s exorcism is so peculiar, particularly the voice she screams in, that it’s hard not to wonder if Friedkin altered the sound in postproduction to intensify the experience. But he’s not tipping his cap, making no mention of it either way. Later in the movie, he dramatizes an (unfilmed) meeting with Cristina that turned sour, shooting an empty church in ridiculously over-the-top fashion and describing their angry confrontation in voice-over.

But, as a filmmaker, Friedkin has long possessed the ability to blend heightened pulp with a hint of realism. It’s what made his Best Picture winner The French Connection such an unusual proposition in 1971; he had folded an international-conspiracy thriller about a European heroin ring into a story about a flea-bitten, take-no-prisoners New York cop. The Exorcist novelist and screenwriter, William Peter Blatty, pushed for Friedkin’s hiring, and The French Connection convinced the studio to bring him aboard.

The stories of the ensuing production are legend. Friedkin once slapped an Exorcist cast member in the face right before calling action, he fired guns on set to startle his actors, and the actress Ellen Burstyn described the filming experience as bruising and grueling (she suffered a permanent spinal injury due to one stunt). The director was no stranger to dramatics, which made the movie the success it still is, as did Blair’s performance as the possessed Regan (voiced by a rasping Mercedes McCambridge).

The Devil and Father Amorth at times seems like it’s trying to set the record straight on exorcisms. Amorth is presented in the kindliest of lights, and the ritual seems to involve little more than intense prayer. But again and again, Friedkin can’t help but come off as an old showman dusting off his bag of tricks—at one point, he even walks the famous steps that feature so prominently in The Exorcist, simply to nudge the audience’s imagination toward his masterwork. He seems proud to have created a piece of art so indelible that it’s overridden the actual details of the rite it’s depicting. The Devil and Father Amorth is a somewhat chintzy celebration of that achievement, and an attempt to capture something authentic about its subject. It’s a director recognizing the comforts, and limits, of his own legacy.

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David Sims is a staff writer at The Atlantic, where he covers culture.